This invention is directed to a shortening management method and apparatus wherein the criteria which cause breakdown of the shortening in a deep fat fryer are evaluated so that the apparatus can signal the operator that the shortening is reaching a state of non-useability.
The above-mentioned U.S. Pat. No. 4,362,094 discloses and claims a cooking time control system which, among other things, can signal the completion of cooking of a food item in a deep fat fryer. That patent describes in detail the manner in which the end of cooking time can be signaled to the cook, through correlating input information on time, temperature and the food material being cooked. This input data is also useful in evaluating the status and expected remaining life of the shortening employed in the cooking, as is described in detail in the following specification.
The types of shortenings used for deep fat frying have been studied, and there is published information on the manner of degradation. Fresh shortening contains triglycerides (a glycerine molecule with three fatty acids attached to it) and other similar complex molecules. When the shortening breaks down, the fatty acids break off. Other things occur, but the fatty acid level is considered to be the best general indicator of the usefulness of the shortening. New shortening has about a 0.03 percent concentration of free fatty acid. As the shortening is used in the deep fat fryer, degradation occurs, and by the time the free fatty acid concentration is about 3 percent, the shortening is substantially unuseable. The taste of the breakdown products builds up in the shortening and, at the 3 percent, the shortening is called rancid.
Some years ago, shortening was comparatively inexpensive and it was not an undue expense to simply throw away the shortening. However, shortening is more expensive in the present market. As a consequence, sometimes the shortening is not changed soon enough and the result is an inferior food product. In order to avoid this, some restaurants are changing their shortening more often than is necessary, with the resultant increase in operating costs.
What is needed is a shortening management method and apparatus by which the various factors affecting shortening life are evaluated, and a signal is emitted to indicate that the effective life of the shortening is substantially at an end.